NAME

VMS::Device - Perl interface to VMS device system calls ($GETDVI and friends)

SYNOPSIS

use VMS::Device;
@type_list = device_types();
@class_list = device_classes();
@dev_list = device_list($DeviceName[, $DeviceClass[, $DeviceType]]);
$DevInfoHashRef = device_info($DeviceName);
$BitmapHashRef = decode_device_bitmap($InfoName, $BitmapValue)
$Status = mount(\%Device_properties);
$Status = dismount($DevName[, \%Dismount_flags]); [Unimplemented]
$DeviceAllocated = allocate($DevName[, $FirstAvail[, $AccMode]]);
$Status = deallocate($DevName[, $AccMode]);
$Status = initialize($DevName[, $VolumeName[, \%DevProperties]]);

DESCRIPTION

VMS::Device mounts and dismounts, allocates and deallocates, initializes, and lists and gets info on devices. It subsumes the DCL commands MOUNT, DISMOUNT, ALLOCATE, DEALLOCATE, and INITIALIZE, as well as the lexical functions F$DEVICE and F$GETDVI.

Functions

device_types

This function returns a list of all the valid device types that can be specified for the device_list function.

device_classes

This function returns a list of all the valid device classes that can be specified for the device_list function.

device_list

The device_list function returns a list of all devices whose names match the passed device name (Standard VMS wildcards of * and % are OK) and that meets the criteria in the optional device type and device class.

Both the device class and device type may be ommitted if you want, or passed as undef. If you use the type and not the class, class must be passed as undef.

device_info

The device_info function returns a reference to a hash containing all the information available about the device you asked about.

decode_device_bitmap

The decode_device_bitmap takes an item code and an integer, and returns a reference to a hash. The function assumes the integer is a bitmap as returned for that particular item, and decodes it. Each element in the returned hash is equivalent to one of the bits in the integer--its value will be true or false depending on the setting of the bit.

mount

mount takes a reference to a hash with the parameters for the mount, and attempts to mount the device. At the very least you want a DEVNAM parameter to specify the device being mounted.

dismount

dismount dismounts the specified device. The optional reference to a flag hash governs how the dismount behaves (whether it's a cluster-wide dismount, for example)

allocate

allocate allocates the named device.

If the $FirstAvail flag is true, then the device name is treated as a device type rather than an actual device, and the first device matching the type that's available will be allocated.

$AccMode is the access mode that the device is allocated in. This can be one of:

KERNEL
EXEC
SUPER
USER

to indicate the mode the device should be allocated in.

deallocate

deallocate deallocates a previously allocated device. The optional second parameter can be one of:

KERNEL
EXEC
SUPER
USER

to indicate the mode the device should be deallocated in.

initialize

Initializes the specified device. If the second parameter isn't undef, it's taken to be the name the initialized volume should have. If the third parameter isn't undef, it's taken to be a reference to a hash that has the properties the newly-initialized volume should have.

EXAMPLES

Here's a sample that returns the total amount of free space on all disk devices:

#! perl -w
use VMS::Device qw(device_list device_info);

$TotalFreeBlocks = 0;
foreach my $devname (device_list("*", "DISK")) {
  $TotalFreeBlocks += device_info($devname)->{FREEBLOCKS};
}

print "Total free is $TotalFreeBlocks\n";

here's one that prints out the disk with the largest amount of free space:

#! perl -w
use VMS::Device qw(device_list device_info);

$FreeBlocks = 0;
$FreeName = "DUAWHOKNOWS";
foreach my $devname (device_list("*", "DISK")) {
  $CheckBlocks = device_info($devname)->{FREEBLOCKS};
  if ($CheckBlocks > $FreeBlocks) {
    $FreeBlocks = $CheckBlocks;
    $FreeName = $devname;
  }
}

print "$FreeBlocks on $FreeName\n";

and here's one that shows all disks with less than 10% free:

#! perl -w
use VMS::Device qw(device_list device_info decode_device_bitmap);

foreach my $devname (device_list("*", "DISK")) {
  $DevHash = device_info($devname);
  $FreeBlocks = $DevHash->{FREEBLOCKS};
  $MaxBlocks = $DevHash->{MAXBLOCK};
  next unless $DevHash->{MOUNTCNT};
  next unless $MaxBlocks;
  $PctFree = int(($FreeBlocks/$MaxBlocks) * 100);
  if ($PctFree < 10) {
    print "Only $PctFree\% on $devname ($FreeBlocks of $MaxBlocks)\n";
  }
}

AUTHOR

Dan Sugalski <sugalskd@ous.edu>

SEE ALSO

perl(1).